As a power factor correction circuit for correcting an input-side power factor, a circuit (so-called booster circuit) including a reactor, a diode, and a switching element has been conventionally proposed. More specifically, the reactor and the switching element are connected in series with each other between two input terminals, and the diode and the switching element are connected in series with each other between two output terminals. The diode is provided with the anode thereof directed to the switching element side. A smoothing capacitor is provided between the two output terminals.
In this circuit, when the switching element is conducting, a current flows in the input terminals via the reactor and the switching element, and when the switching element is non-conducting, a current flows in the input terminals via the reactor, the diode, and the output terminals. This increases the conducting angle of an input current, and thereby corrects an input-side power factor.
A power factor correction circuit including two such circuits has been also proposed. In such a power factor correction circuit, switching elements belonging to the two circuits are rendered conducting at different timings. This power factor correction circuit is referred to as a so-called interleave type power factor correction circuit.
Moreover, Japanese Patent Application Laid-Open No. 11-289766 (1999) is disclosed as a technique related to the present invention.